An electron emission device (EED) generally comprises a display apparatus from which an arbitrary image is realized when electrons emitted from an electron emitting region of a cathode electrode irradiate. The electrons irradiate through the tunneling effect of quantum mechanics, by colliding with a phosphor layer formed on an anode. A triode consisting of a cathode electrode, a gate electrode, and an anode electrode is a widely used structure for an EED.
A commonly used triode consists of a vacuum container comprising a rear substrate comprising a cathode electrode and a gate electrode and a front substrate comprising an anode electrode. The vacuum container is put together using a sealant, such as a frit. The vacuum container includes several spacers creating a fixed gap between the rear and front substrates to keep the rear substrate away from the front substrate.
An arc discharge is generated in the vacuum container by the electron emission device. It can be inferred that the arc discharge is generated by the simultaneous ionization of a great deal of gas by outgassing, which occurs in the vacuum container. Generally, the arc discharge generated becomes more severe as the anode voltage increases. Due to this arc discharge, the gate electrode can be easily damaged because the anode electrode can be electrically shorted with the gate electrode.
To resolve this problem, an electron emission device has been proposed in which a metal grid electrode is equipped between the rear substrate and the front substrate. The grid electrode can protect the electrodes equipped on the rear substrate from damage due to generation of the arc discharge, and improves the capability of focusing the emitted electrons.
However, when the thermal expansion coefficient of the metal grid electrode differs remarkably from the thermal expansion coefficient of heat-reinforced glass used for the front and rear substrate of a flat panel display, several problems occur during the sealing and exhaust processes of the electron emission device. One such problem is the limited availability of high temperature processes. Another problem is that the panel can be damaged during the exhaust process when the grid electrode and underplate are misaligned. Moreover, electrons emitted from the electron emitting region may collide with the phosphor layer of a surrounding territory instead of the selected territory due to the misalignment of the grid electrode, and the color purity can depreciate.
To solve these problems, a design has been introduced which compensates for the misalignment of the grid electrode generated during the heat treatment process. However, this design uses a troublesome process and has certain limitations in quality control.